Electrical line terminal block



Feb. 19, 1957 o. A. VORDTRIEDE ELECTRICAL LINE TERMINAL BLOCK Filed Feb. 4, 1953 2,782,393 Patented Feb. 19, 1957 ELECTRICAL LINE TERMINAL BLOCK Oliver A. Vordtriede, St. Louis, Mo., assignor, by mesne assignments, to A. E. Chance Company, Centralia, Mo a corporation of Missouri Application February 4, 1953, Serial No. 335,049

Claims. (Cl. 339-272) This invention relates to electrical line terminal blocks, and with regard to certain more specific features, to such a block incorporating spring pressure bars in its wire receiving socket.

Among the several objects of the invention may be noted the provision of an improved terminal block incorporating spring pressure bars which provide for convenient acceptance of a large range of wire diameters; the provision of such bars including pads for preventing scoring of accepted wires by certain tightening screws; the provision of a terminal block of the class described wherein the pressure bars are arranged for a maximum flexibility and screw-following movements of the pads, with minimum internal stresses in the bars; the provision of a block of the class described wherein the pressure bars are held captive by floating connections further adapted to minimize stresses; and the provision of apparatus of the class described which is compact in form and economical to manufacture and assemble. Other vobjects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the construction hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. l is an isometric view of apparatus embodying the invention;

Fig. 2 is a front elevation, being viewed in the direction of the arrow indicated on Fig. 1 and showing certain clips in retracted positions;

Fig. 3 is a plan view of Fig. 2; Fig. 4 is an end elevation of Fig. 3'; Fig. 5 is a longitudinal section taken on line 55 of Fig. 3 but showing said clips in advanced positions in contact with certain conductors shown in dotted lines;

Fig. 6 is a plan view of a spring pressure bar removed from the assembly; and,

Fig. 7 is a front elevation of Fig. 6. An exemplary application of the present invention will be understood by reference to the United States Patent 2,668,209 of James J. Cooper and myself, for Fuse Cut out. In that patent is shown an electrical line terminal block cemented into an electrical switch. The general purpose of such a block is conductively to receive and clamp in its socket one or more line terminal wires. It will be understood that the terminal block may form a part of other electrical devices upon which line terminal blocks are required.

Briefly, the invention comprises an electrical line terminal block having a tubular wire socket open at least at one end and having a first threaded opening on one side of the socket adjacent said end and also having a second threaded opening on the same side adjacent the other end. A first pressure screw is threaded through the opening adjacent the first end and a second pressure screw is threaded through the second opening. The device includes at least one pressure bar composed of a cantilever spring strip formed as a U-shape at one end and having aligned openings for loosely receiving the first screw which acts as an anchor. This strip includes a cantilever extension reaching from the open end of the socket to the other end. The free end of the cantilever acts as a pressure pad springingly engaging the end of the second pressure screw. The invention consists further in having both ends of the socket open, with two of the stated bars oppositely directed and intermediately notched, so as to interdigitate the pads in alignment within the socket. Each screw acts then loosely to hold captive one strip while acting also as a pressure means on one of the pads. Each pad protects any inserted wire from scoring action by the screw end located behind the pad.

Referring now more particularly to the drawings, there is shown at numeral 1 a tubular or parallelepiped body having a fiat top wall 3, parallel 'flat side walls 5 and 7, and a trough or V-shaped bottom '9. There is thus formed a passage 11 having opposite open ends for receiving a large size range of wire or wires to be fastened. On the wall. 5 is a conductive contact pad 13, adapted to be engaged by suitable contact springs, brushes or the like, of apparatus which the invention serves. Numeral 14 indicates reinforcing ribs. At 15 is shown an anchor piece adapted to be cemented or otherwise fastened in position within a suitable socket of the apparatus served by the device. Such apparatus is not shown because it may be any of many forms.

Combined anchor and pressure screws 17 are threaded into threaded openings 18 near the ends of the top 3, as indicated more particularly in Figs. 2, 3 and 5. At 19 are shown identical but reversely positioned spring bars, one of which is detailed in Figs. 6 and 7. Each bar is composed of a flexible strip of conductive spring material such as phosphor bronze. The widths are in general slightly less than the distance between parallel walls 5 and 7. Each strip is bent into a U-shape 21 at one end. At its other end it is angled to form a pressure contact pad 23. At the end of the pad is an angled lip 25. Between its ends each strip is notched out to a depth of slightly more than half its width, as indicated at numeral 27. In opposite legs of the U-shape 21 are openings 29, suiflciently large to receive loosely the screws '17.

In assembly, a pair of the bars 19 is reversely positioned end for end and side by side, and introduced into the opening 11, after which the U-shaped portions 21 are caused springingly to hook over and embrace or envelope the ends of the top 3. During assembly the parts of the bars 19 which extend from the U-shapes 21 are arranged in side elevation to cross over one another at the adjacent notches 27 (see Fig. 5). This interdigitates the remaining portions of the pressure bars 19 in the opening 11. Thus when the openings 29 are in general alignment with threaded openings 18, the pressure screws 17 may be threaded through openings 18, thus loosely to hold the bars 19 captive without tightly anchoring them .to the top 3. This assembly places opposite pads 23 below the lower ends 31 of opposite pressure screws 17. Polygonal heads 33 on the screws provide for wrench engagement. Thus each screw loosely holds one bar captive and acts as a pressure means on the pad of the other bar.

Operation is as follows:

By unthreading the screws 17, the bars 19 tend to spring into their forms as shown in Figs. 6 and 7, thereby causing the pads 23 to follow the retracting ends 31 of the screws 17. This opens the passageway 11 for reception of a wire or wires, lips 25 facilitating this. Upon threading in either screw 17, its respective end 31 forces down the respective pad 23 so that under pressure the pad conductively engages the inserted wire or wires, which are thus also wedged in the V-shaped bottom 9.

Advantages of the invention include the following: The pads 23 are at the ends of long spring members which may be designated as cantilever springs 35 (Fig. 6). Unlike former structures the cantilever springs are of maximum length for a given length of opening 11. This is due to the cross-over arrangement between them. Therefore, they have maximum deflections with minimum induced stresses, which permit the block to accommodate a larger range of wire sizes or number of wires. Moi-- over, the U-shaped portions 21, being loosely held captive by the screws 17, do not tend to set up excessive stresses at corners, such as shown at 37. For example, when the pads 23 are depressed, movements are distributed throughout the U-shapes 21, thus minimizing corner stresses. The result of the combination of the long cantilever springs 35 and the loosely anchored U-shaped ends provides a spring arrangement having long life. At the same time, the stated large range of wire sizes and numbers may be accommodated. Moreover, by retracting the screws 17, the follow-up action of pads 23 serves automatically to form a large receiving opening into which the wire may be easily introduced, even with heavily gloved hands. Neither in assembly nor in operation is any finesse required of operators. The pads prevent the rotating ends of the screws from scoring the inserted wires.

The openings 29, which are within the passage 11, are such as to allow the required substantial deflections of the cantilever spring extensions 35 and pads 23 without interference from the screws 17. And in addition, the inside and outside openings 29 form means whereby the screws 17 loosely hold captive the spring pressure bars 19.

Assembly is convenient. For this purpose screws 17 are removed. The bars 19 are interdigitated outside of the passage 11, resulting in an interdigitated subassembly of the two bars 19. This subassembly is inserted into the passage 11, and one U-shape 21 at a time is pressed upward and axially to envelope an end of the wall 3. This aligns opening 29 with openings 18 and the screws 17 are then inserted. Before insertion of the screws, the subassembly fairly maintains a preliminary assembled relation with the body 1, which facilitates operations.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. An electrical line terminal block comprising a tubular socket open at both ends and having threaded open ings on one side of the socket and respectively adjacent said ends, screws respectively threaded through said openings, two bars, each of which is composed of a spring strip formed as a U-shape at one end and having aligned openings in the U-shape,the U-shape of each bar embracing one end of the socket with one of said openings outside and the other opening inside of the socket, each of said screws passing through the respective openings of one of the bars, each bar having a cantilever extension reaching from one open end substantially to the other open end of said socket, said extensions being directed oppositely within the socket, the end of each extension springingly engaging the end of the screw that passes through the openings of the other bar.

2. An electrical line terminal block made according to claim 1, wherein the width of each of said cantilever extensions approximates the width of said socket, said extensions being notched at portions intermediate their ends and within the socket, at which portions they cross one another so as to interdigitate the remaining portions of the extensions for alignment within the socket.

3. An electrical line terminal block comprising a tubular socket having open ends and having an interior upper wall, interiorly substantially fiat parallel side walls and a trough-shaped bottom wall, said upper wall having threaded openings near said open ends, bars composed of spring strips of general widths slightly less than the distance between said side wall interiors and having U-shapes enveloping the ends of the upper wall, each bar having a spring cantilever extension from its U-shape reaching interiorly through the socket substantially from end to end and being intermediately notched for crossed interdigitation with the other extension within the socket, the free ends of the extensions being formed as pressure pads which are aligned within the socket, and pressure screws threaded through said openings in the upper wall, said openings in the respective U-shapes loosely surrounding said screws respectively outside ano inside of the upper wall, whereby each screw loosely holds captive each bar at its U-shape and is adapted to be springingly engaged by one of said pads.

4. An electrical line terminal block made according to claim 3, wherein the legs of the U-shapes are formed to be nonparallel to the upper wall and wherein said pads include lips extending from the ends of said socket and away from said trough-shaped bottom wall.

5. An electrical line terminal block comprising a parallelopiped socket having open ends and having a first wall, parallel side walls which interiorly are substantially parallel and a V-shaped wall, said first wall having threaded openings near said ends, bars composed of spring strips of widths generally approximating the distance between the insides of said side walls and having U-shapes springingly enveloping the ends of the first wall, each bar having a cantilever extension from its U-shape and reaching interiorly through the socket substantially from end to end and being intermediately provided with a notch of substantial length and of depth approximately one half of the extension width for crossed interdigitation of the extensions within the socket, the ends of the cantilever extensions being formed as pads located within the socket, and pressure screws threaded through said openings in the first wall, said openings in the respective U-shapes loosely surrounding said screws respectively outside and inside of the first wall, whereby each screw loosely holds captive each U-shape and is springingly engaged by one of said pads for applying pressure thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,266,441 Finkelstein May 14, 1918 1,988,567 Pontus Jan. 22, 1935 2,193,202 Millermaster Mar. 12, 1940 

